Usually, precast concrete(PC) slabs are designed as simply supported elements with structural topping concrete. However, designing for continuity over supports leads to improved structural capacity and savings in material. In this paper, an experimental and theoretical study on the effect of end filling length on the behavior of invertedly ribbed PC slab is presented. 5 connection specimens having different end filling lengths(0, 300, 600, 900mm and full span) were tested under three point loading to simulate the portion of a continuous span in negative bending moment. Each specimen consists of two invertedly ribbed PC slab components on a supporting beam element and is connected by concrete topping with EPS(expanded polystyrene) installed in the space between the ribs except for the end filling lengths. Test results show that the specimen of 300mm concrete filling length has the flexure-shear combined failure mode. Also the shear strength of specimen with 300mm filling length according to KBC2009 eq.(0507.3.3) could be overestimated at the starting point of EPS.